In this paper, we have proposed an efficient fault diagnosis and localization algorithm for Successive-Approximation Register Analog to Digital Converters (SAR ADCs). A wide range of faults on ADC analog and digital parts, as well as faults on input signals are considered. The proposed algorithm uses a built-in self-test (BIST), which implies at-speed test of an ADC using histogram method. After the test is completed, the data collected during production test is stored in a memory and in special registers. Based on this information, fault diagnosis and localization of ADC faults are done.